﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web.UI;
using System.IO;
using System.Web.Hosting;

namespace GoShopping.Utility
{
    /// <summary>
    /// 处理Web路径
    /// </summary>
    public class WebPath
    {

        /// <summary>
        /// 将Web站点下的绝对路径转换为相对于指定页面的虚拟路径
        /// </summary>
        /// <param name="page">当前页面指针，一般为this</param>
        /// <param name="specifiedPath">绝对路径</param>
        /// <returns>虚拟路径, 型如: ../../</returns>
        public static string ConvertSpecifiedPathToRelativePathForPage(Page page, string specifiedPath)
        {
            // 根目录虚拟路径
            string virtualPath = page.Request.ApplicationPath;
            // 根目录绝对路径
            string pathRooted = HostingEnvironment.MapPath(virtualPath);
            // 页面虚拟路径
            string pageVirtualPath = page.Request.Path;
            if (!Path.IsPathRooted(specifiedPath) || specifiedPath.IndexOf(pathRooted) == -1)
            {
                throw new Exception(string.Format("{0}是虚拟路径而不是绝对路径!", specifiedPath));
            }
            // 转换成相对路径
            //(测试发现，pathRooted 在 VS2005 自带的服务器跟在IIS下根目录或者虚拟目录运行似乎不一样,
            // 有此地方后面会加"", 有些则不会, 为保险起见判断一下)
            if (pathRooted.Substring(pathRooted.Length - 1, 1) == @"\")
            {
                specifiedPath = specifiedPath.Replace(pathRooted, "/");
            }
            else
            {
                specifiedPath = specifiedPath.Replace(pathRooted, "");
            }
            string relativePath = specifiedPath.Replace(@"\", @"/");
            string[] pageNodes = pageVirtualPath.Split('/');
            // 减去最后一个页面和前面一个 "" 值
            int pageNodesCount = pageNodes.Length - 2;
            for (int i = 0; i < pageNodesCount; i++)
            {
                relativePath = "/.." + relativePath;
            }
            if (pageNodesCount > 0)
            {
                // 如果存在 ".." , 则把最前面的 "/" 去掉
                relativePath = relativePath.Substring(1, relativePath.Length - 1);
            }
            return relativePath;
        }

        /// 
        /// 将Web站点下的绝对路径转换为虚拟路径
        /// 注：非Web站点下的则不转换
        /// 
        /// 当前页面指针，一般为this
        /// 绝对路径
        /// 虚拟路径, 型如: ~/
        public static string ConvertSpecifiedPathToRelativePath(Page page, string specifiedPath)
        {
            string virtualPath = page.Request.ApplicationPath;
            string pathRooted = HostingEnvironment.MapPath(virtualPath);
            if (!Path.IsPathRooted(specifiedPath) || specifiedPath.IndexOf(pathRooted) == -1)
            {
                return specifiedPath;
            }
            if (pathRooted.Substring(pathRooted.Length - 1, 1) == @"\")
            {
                specifiedPath = specifiedPath.Replace(pathRooted, "~/");
            }
            else
            {
                specifiedPath = specifiedPath.Replace(pathRooted, "~");
            }
            string relativePath = specifiedPath.Replace(@"\", @"/");
            return relativePath;
        }

    }
}
